Interbody spacers are used as aids in various spinal surgeries. When a spinal disc has suffered disease or trauma, degeneration of one or more discs may result. Depending on the medical indications of the damaged spine, a surgical treatment may be called for. For example, spinal surgeries may call for the full or partial removal of a spinal disc. In other procedures, an implant or support may be used to stabilize elements of the spine in order to assist in the healing process. Various devices have been developed, some known as interbody spacers or spreaders, for use in one or more spinal surgeries. While these devices can be used in a variety of different surgeries and treatments, in several known surgical procedures it is necessary to physically implant an interbody spacer in a desired location relative to the spine. Later, depending on the treatment, the interbody spacer may or may not be removed from the patient.
However, the existing spacers suffer from a limited ability to extract and reposition the interbody spacer device. The limitation on repositioning is noted both during the initial placement and also later after the initial placement has occurred. This limitation is experienced in current devices, systems, and surgical procedures. This limitation introduces additional potential risks to the patient. With current systems and procedures, the need to remove or reposition an interbody spacer can present a significant risk to the patient's spinal cord, nerve roots, and dural sack. The fear of working with extraction tools in close proximity to the spinal cord may lead surgeons to perform more invasive techniques, such as a partial corpectomy, to retrieve the device without damaging the spinal cord. Similarly, a surgeon may settle for an imperfect placement due to the risk associated with introducing tools to reposition the device and a lack of options for repositioning. Hence, in order to overcome these limitations, it would be desired to provide an interbody spacer device that provides increased movement and flexibility after the initial positioning.
The device described herein allows a retrieval tool to be locked into the spacer block to ease removal or repositioning of the innerbody spacer. It can be configured in dimensions appropriate for transforaminal lumbar interbody fusion (TLIF), posterior lumbar interbody fusion (PLIF), and anterior lumbar interbody fusion (ALIF) procedures and is not limited to any one technique. The block is inserted using a newly developed threaded rod assembly using an insertion technique that is similar to techniques currently described by other manufacturers of TLIF devices. The device would preferably be manufactured from a material such as a PEEK or similar material. The block could be offered with multiple angle and height options to restore the proper lordosis and spacing at the level of fusion. The block contains voids with interconnections to allow bone graft or bone substitute to be packed inside and to promote tissue ingrowth within the spacer.
One innovation is the incorporation of an extraction tool that can be inserted and locked into the implant, allowing it to be pulled out with the aide of a slap hammer, or other surgical hammer, that allows for incremental movements and mitigates the risk of damaging the dural sac or spinal cord. The extraction tool consists of a blunt face “key” that can be passed into the spacer block and is then rotated 90 degrees to a positive stop so it cannot be withdrawn.
In most cases the need to remove the device will become apparent before significant tissue ingrowth and bone fusion have occurred. This may be due to incorrect initial positioning by the surgeon, infection shortly after surgery, or failure of a vertebral body. These issues usually become apparent within several weeks after initial surgery.
In the event that the implant has been in place for some time and significant scar tissue or trabecular bone ingrowth has occurred, an alternative tool, with a much sharper profile can be used to clear the inner void of the spacer and improve the chances of recovering the implant without resorting to more invasive methods.